This invention relates to a connector for anchoring a first building structural member to a second building structural member. The connector works in conjunction with a separate anchor member that is received by or is attached to the second building structural member and with fasteners for attaching the connector to the first building structural member.
Earthquakes, hurricanes, tornadoes, and floods impose forces on a building that can cause structural failure. To counteract these forces, it has become common practice to strengthen or add ties between the structural members of a building in the areas of the building where these cataclysmic forces may be concentrated. For example: framed walls can be attached to the foundation rather than merely rest on it; connections between the framed walls of each floor can be strengthened; and joists can be connected to both their headers and the walls that support the headers. One of the most common connectors designed for this application is called a holdown by the inventor. Holdowns are commonly used to anchor framed walls to the foundation.
Early holdowns were constructed from two or more separate pieces of metal welded together. These holdowns had to be painted to prevent rusting. They were heavy and costly to produce.
State of the art holdowns are made from galvanized sheet metal formed on progressive die machines that require no welding or painting. See U.S. Pat. No. 4,665,672, granted May 19, 1987, to Commins, Gilb and Littleton; U.S. Pat. No. 5,092,097 granted Mar. 3, 1992, to Young; and U.S. Pat. No. 5,249,404, granted Oct. 5, 1993, to Leek and Commins. These advancements have reduced the cost of making holdowns while increasing their ability to withstand tension forces. However, severe earthquakes in San Francisco, Los Angeles, and Kobe, Japan, demonstrate that holdowns capable of being mass produced and installed inexpensively should be made even stronger for many connections.
Typical holdowns work in conjunction with a separate anchor memberxe2x80x94and attach to the side face of the first building structural member generally a vertically disposed stud in vertical applications in walls. In these holdowns that attach to the side of a stud or post, the anchor member attaches at the seat of the connector. This seat is connected to a back member, and the back member attaches to the side face of the stud or post. Often, these holdowns have one or more side members 9 to increase the strength of the connector or to connect the seat member to the back member.
Another style of holdown attaches to the bottom end of the stud or post. A patented example of this type of holdown is found in U.S. Pat. No. 5,375,384, granted to Yehuda Wolfson on Dec. 27, 1994. The advantage of a holdown that attaches to the bottom end of a post or stud is that it can remove any eccentricity from the connection. The holdown of the present invention is this type of holdown.
The holdown connector of the present invention improves upon the prior art by providing a holdown that withstands very high tension loads with minimal deflection, while being economical to produce.
The present invention is a connection between a first building structural member and a second building structural member using a connector, an anchor member and fasteners.
The anchor member is held by the second building structural member. The anchor member has a first end which protrudes above the second building structural member. A connector receives the first end of the anchor member. The connector consists of a channel-shaped strap and a standoff base. The strap has a base and two side members 9. The base of the strap is formed with an opening for receiving the anchor member there through. The separate standoff base, which is received between the side members 9 of the strap and rests on said base of the strap, is formed with an opening for receiving the anchor member. The standoff base is connected to the anchor member. A first building structural member is received between the side members 9 of the strap. This member rests on and is supported by the top of the standoff base which lifts the bottom of the first structural building member above the first end of said anchor member. Fasteners complete the connection by connecting the side members 9 of the strap to the first building structural member.
The object of the present invention is to provide a connector that better withstands tension forces than the prior art, while still being economical to produce and simple to install.
The connector of the present invention has been tested, and found to have very high design loads. An embodiment of the connector of the present invention which is formed to anchor a 4xc3x974 post or two sistered 2xc3x974 studs and uses 24 2.5xe2x80x3 Simpson Strong-Drive wood screws has been found to have a design load of 9735 pounds. This design load is based on a static load tests conducted on a steel jig, using wood posts. The design load is the lowest of three different possible measures of the strength of the connection: the value at which the holdown deflects 0.125xe2x80x3, the deflection being measured as the movement in the connection due to movement of the connector between the anchor bolt and the strap portion of the holdown; the load at which failure of the connection occursxe2x80x94ultimate loadxe2x80x94divided by 3, or the calculated values for 24 wood screws loaded in shear and connecting a wood member to a 10 gauge steel strap.
A further object of the present invention is to provide a base for the first building structural member that resists design compression loads. The preferred base is formed from cast aluminum, making it very strong.
A further object of the present invention is to provide a connector that does not create any eccentric loading. This is accomplished by setting the post that is anchored by the connector directly over the point where the connector attaches to the bolt or anchor member.
A further object of the present invention is to provide a connector that accommodates variations in the position of the anchor member parallel to the face of the first building structural member to which the holdown connector attaches. This object is achieved by forming the connector with a relatively wide opening for receiving the anchor member.
The object of making a holdown that is economical to produce is achieved by utilizing a design that can be formed on automated machinery with a minimum of costly secondary operations, such as painting and welding.
These and other objects of the present invention will become apparent, with reference to the drawings, the description of the preferred embodiment and the claims.